With downloads of XP Service Pack Two due to begin on Monday, Microsoft is bracing itself for an expected flood of requests from users.
On Monday morning US time (6.00pm in the UK) Windows users with Automatic Update turned on will be able to start downloading the 80MB (compressed) patch, albeit slowly at first.
Microsoft estimates that 40 per cent of UK users use its Automatic Update service.
"We won't be at full capacity on Monday. We'll be throttling the number of users who can download it," said Paul Randle, product marketing manager for SP2.
"We want to make sure that the customer experience is as good as it can be. Then by the end of the month users can order CDs from us totally free of any charge. You should see the size of our postage bill!"
The new code will also be available on magazine cover mounts in September and will be distributed in stores, although it will be kept behind the counter and given to those who ask rather than left in drop bins in shops.
The Automatic Update service is being beefed up to allow the software to recognise the kind of computer and connection the user has.
Dial-up users, for example, can download SP2 in the background while working. If they want to check email or use bandwidth in other ways the SP2 download slows or stops, and then resumes when bandwidth is available.
This feature will also allow Tablet PC users to be identified and issued with the new Tablet PC 2005 software, codenamed Lonestar.
The new code, which will give improved handwriting recognition, unlocks the input panel and a new software development kit for the platform.
"Lonestar will be a benefit for users but won't increase overall Tablet PC sales," said Mike Welsh, vice president of analyst Canalys.
"These are genuine improvements, [but] they won't overcome the flaws in the Tablet PC: the price differential, the lack of applications and foreign language support."
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